U.S. patent number 6,299,778 [Application Number 09/308,221] was granted by the patent office on 2001-10-09 for catalytically active permeable composite material, method for producing said composite material, and use of the same.
This patent grant is currently assigned to Creavis Gesellschaft fuer Technologie und Innovation mbH. Invention is credited to Mark Duda, Gerhard Hoerpel, Christian Hying, Adolf Kuehnle, Bernd Penth.
United States Patent |
6,299,778 |
Penth , et al. |
October 9, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
Catalytically active permeable composite material, method for
producing said composite material, and use of the same
Abstract
The invention relates to a catalytically active, permeable
composite material, a method for producing said composite material,
and the use of the composite material. The inventive composite
material can be used for separating mixtures of materials. The fact
that various catalytically active substances can be incorporated
into the material in various ways makes it highly flexible in terms
of possible applications with properties which can be adapted to
the particular purpose of an application. The inventive composite
material can be used as a catalytically active membrane electrode,
for example. According to the invention, the material is obtained
by solidifying a suspension on and in a porous, permeable support.
The production of the material requires either a very short period
of heat treatment at temperatures of around 400.degree. C. or
treatment for a longer period at very mild temperatures of below
100.degree. C.
Inventors: |
Penth; Bernd (Lebach,
DE), Hying; Christian (Rhede, DE), Duda;
Mark (Marl, DE), Hoerpel; Gerhard (Nottuln,
DE), Kuehnle; Adolf (Marl, DE) |
Assignee: |
Creavis Gesellschaft fuer
Technologie und Innovation mbH (Marl, DE)
|
Family
ID: |
27512604 |
Appl.
No.: |
09/308,221 |
Filed: |
July 28, 1999 |
PCT
Filed: |
September 18, 1998 |
PCT No.: |
PCT/EP98/05938 |
371
Date: |
July 28, 1999 |
102(e)
Date: |
July 28, 1999 |
PCT
Pub. No.: |
WO99/15272 |
PCT
Pub. Date: |
April 01, 1999 |
Foreign Application Priority Data
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Sep 20, 1997 [DE] |
|
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197 41 498 |
Mar 18, 1998 [DE] |
|
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198 11 708 |
Mar 18, 1998 [DE] |
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198 12 035 |
May 8, 1998 [DE] |
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198 20 580 |
Jun 3, 1998 [DE] |
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198 24 666 |
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Current U.S.
Class: |
210/650; 204/554;
210/490; 210/500.25; 264/45.1; 428/307.7; 55/524; 55/523;
427/372.2; 210/500.26 |
Current CPC
Class: |
B01D
46/0056 (20130101); B01D 46/24 (20130101); B01D
46/4263 (20130101); B01D 46/48 (20130101); B01D
46/521 (20130101); B01D 53/228 (20130101); B01D
53/32 (20130101); B01D 53/8675 (20130101); B01D
53/885 (20130101); B01D 67/0041 (20130101); B01D
67/0048 (20130101); B01D 67/0069 (20130101); B01D
67/0072 (20130101); B01D 67/0093 (20130101); B01D
69/141 (20130101); B01D 71/02 (20130101); B01D
71/024 (20130101); B01D 71/028 (20130101); B01J
35/06 (20130101); B01J 37/0215 (20130101); B01J
37/0225 (20130101); B01J 37/033 (20130101); B01D
46/0068 (20130101); Y10T 428/249957 (20150401); B01D
2265/06 (20130101); B01D 2323/08 (20130101); B01D
2325/02 (20130101); Y10S 55/10 (20130101) |
Current International
Class: |
B01J
35/06 (20060101); B01J 37/02 (20060101); B01J
37/00 (20060101); B01J 37/03 (20060101); B01J
35/00 (20060101); B01D 46/48 (20060101); B01D
46/24 (20060101); B01D 53/86 (20060101); B01D
53/22 (20060101); B01D 53/32 (20060101); B01D
71/00 (20060101); B01D 71/02 (20060101); B01D
53/88 (20060101); B01D 006/100 (); B01D 071/02 ();
B01D 071/04 () |
Field of
Search: |
;210/500.25,500.26,490,505,508,510.1 ;264/45.1,44,46.4 ;428/327.7
;427/372.2 ;485/920 ;55/423,424 ;204/554 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
0263468 |
|
Oct 1987 |
|
EP |
|
0332789 |
|
Mar 1988 |
|
EP |
|
0426546 |
|
Oct 1990 |
|
EP |
|
0585152 |
|
Jul 1993 |
|
EP |
|
0778076 |
|
Nov 1996 |
|
EP |
|
96/00198 |
|
Jan 1996 |
|
WO |
|
Other References
A Julbe et al, The sol-gel approach to prepare candidate
microporous inorganic membranes for membrane reactors, Journal of
Membrane Science, 77 (1993) 137-153, Elsevier Science Publishers B.
V., Amsterdam..
|
Primary Examiner: Fortuna; Ana
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
What is claimed is:
1. Catalytically active permeable flexible composite based on at
least one perforated and permeable carrier, which contains on at
least one side of the carrier and inside the carrier at least one
inorganic component, which consists essentially of at least one
compound of a metal, a metalloid or a composition metal and at
least one element from group III to VII of the periodic system,
which permeable flexible composite is obtained by application of a
suspension, which contains said at least one inorganic component
and a sol, on and inside at least one flexible, perforated and
permeable carrier, and stabilizing the suspension by heating the
suspension at least once either at a temperature of between 50 and
100.degree. C. for 10 minutes to 5 hours, or at a temperature of
between 100 and 800.degree. C. for 1 second to 10 minutes,
wherein said composite can be wound on or off a roll.
2. Composite according to claim 1, wherein the composite is
permeable for gases, solids or liquids.
3. Composite according to claim 1, wherein the composite is
permeable for particles with a size of 0.5 nm to 10 .mu.m.
4. Composite according to claim 1, wherein the perforated and
permeable carrier contains gaps with a size of 0.02 to 500
.mu.m.
5. Composite according to claim 1, wherein the carrier contains at
least one of the following materials: carbon, metals, alloys,
glass, ceramic materials, minerals, plastics, amorphous substances,
natural products, composites or at least one combination of these
materials.
6. Composite according to claim 1, wherein the carrier was modified
with at least one of the following processes: thermal, mechanical
and chemical treatment or a combination of these treatment
processes.
7. Composite, according to claim 1, wherein the carrier contains at
least one metal or one natural fiber or one plastic and has been
modified according to at least one mechanical deformation
technology.
8. Composite according to claim 7, wherein the at least one
mechanical deformation technology is selected from the group
consisting of drawing, swaging, milling, stretching and
forging.
9. Composite according to claim 1, wherein the carrier contains at
least woven or felted or ceramically bound fibers or at least
sintered spheres or particles.
10. Composite according to claim 1, wherein the carrier is
perforated.
11. Composite according to claim 1, wherein the permeable carrier
has been made permeable by laser or ion beam treatment.
12. Composite according to claim 1, wherein tHe carrier contains
fibers from at least one of the following materials: carbon,
metals, alloys, ceramic materials, glass, minerals, plastics,
amorphous substances, natural products, composites or at least one
combination of these materials.
13. Composite according to claim 1, wherein the carrier contains at
least woven fibers made from metal or alloys.
14. Composite according to claim 1, wherein the carrier contains at
least one mesh made from steel.
15. Composite according to claim 1, wherein the carrier contains at
least one mesh with a mesh width of 5 to 500 .mu.m.
16. Composite according to claim 1, wherein the carrier contains at
least one expanded metal with a mesh width of 5 to 500 .mu.m.
17. Composite according to claim 1, wherein the carrier contains a
sintered metal, a sintered glass or a metallic fleece with a pore
width of 0.1 to 500 .mu.m.
18. Composite according to claim 1, wherein the carrier contains at
least aluminum, silicium, cobalt, manganese, zinc, vanadium,
molybdenum, indium, lead, bismuth, silver, gold, nickel, copper,
iron, titanium, platinum, stainless steel, steel or brass or an
alloy of these materials or a material coated with Au, Ag, Pb, Ti,
Ni, Cr, Pt, Pd, Rh, Ru and/or Ti.
19. Composite according to claim 1, wherein said at least one
metal, metalloid or composition metal of said at least one compound
contains at least one transition element and element of group III
to V of the periodic system, or at least one transition element, or
at least one element of group III to V of the periodic system,
whereby the compounds have a particle size of 0.001 to 25
.mu.m.
20. Composite according to claim 9, wherein the at least one
element from group III to VII of the periodic system of said at
least one compound contains at least one of the elements Te, Se, S,
O, Sb, As, P, N, Ge, Si, C, Ga, Al or B.
21. Composite according to claim 20, wherein the inorganic
component contains at least one compound containing at least one of
the elements Sc, Y, Ti, Zr, V, Cr, Nb, Mo, W, Mn, Fe, Co, B, Al,
In, Tl, Si, Ge, Sn, Pb, Sb or Bi with at least one of the elements
Te, Se, S, O, Sb, As, P, N, C, or Ga or at least one of these
elements.
22. Composite according to claim 1, wherein the inorganic component
contains alumosilicate, aluminum phosphate, zeolite or partially
substituted zeolite.
23. Composite according to claim 1, wherein the inorganic component
contains amorphous microporous mixed oxides that can contain up to
20% non-hydrolyzable organic compounds.
24. Composite according to claim 1, wherein the composite contains
at least two particle size fractions of at least one inorganic
component.
25. Composite according to claim 24, wherein the particle size
fraction in the composite contains a particle size ratio of 1:1 to
1:100.
26. Composite according to claim 25, wherein the composite contains
a quantitative proportion of particle size fraction of between 0.01
to 1 and 1 to 0.01.
27. Composite according to claim 1, wherein the permeability of the
composite can be limited to particles of a certain maximum size by
the particle size of the inorganic component used.
28. Composite according to claim 1, wherein the suspension
containing at least one inorganic component contains at least one
liquid from the following: water, alcohol, and acid or a
combination of these liquids.
29. Composite according to claim 1, wherein the composite as a
catalytically active component contains at least one inorganic
material, at least one metal or at least one organo-metallic
compound, on the surface of which there are catalytically active
centers.
30. Composite according to claim 29, wherein the composite contains
a zeolite, silicalite or an amorphous microporous mixed oxide
system as a catalytic component.
31. Composite according to claim 29, wherein the composite contains
at least one oxide from at least one of the elements Mo, Sn, Zn, V,
Mn, Fe, Co, Ni, As, Sb, Pb, Bi, Ru, Re, Cr, W, Nb, Hf, La, Ce, Gd,
Ga, In, Tl, Ag, Cu, Li, K, Na, Be, Mg, Ca, Sr and Ba as a
catalytically active component.
32. Composite according to claim 29, wherein the composite contains
at least titanium suboxide as a catalytically active component.
33. Composite according to claim 29, wherein the composite contains
at least one metallic compound as a catalytically active component
from compounds of the following metals: Pt, Rh, Ru, Ir, Au, Ag, Os,
Re, Cu, Ni, Pd and Co.
34. Composite according to claim 29, wherein the composite contains
at least one metal as a catalytically active component from the
following metals: Pt, Rh, Ru, Ce, Ir, Au, Ag, Os, Re, Cu, Ni, Pd
and Co.
35. Composite according to claim 1, wherein the composite is
flexible to a smallest radius of up to 1 mm.
36. Process of preparing the catalytically active, permeable
composite as claimed claim 1, comprising applying said suspension
on and inside said at least one flexible, perforated and permeable
carrier, and stabilizing the suspension by heating the suspension
at least once either at a temperature of between 50 and 100.degree.
C. for 10 minutes to 5 hours, or at a temperature of between 100
and 800.degree. C. for 1 second to 10 minutes.
37. Process according to claim 36, wherein the suspension is
applied onto or into or onto and into at least one carrier by
stamping on, pressing on or in, rolling on, applying with a blade
or brush, dipping, spraying, or pouring.
38. Process according to claim 36, wherein a perforated and
permeable carrier is used that contains one of the following
materials: carbon, metals, alloys, glass, ceramic material,
minerals, plastics, amorphous substances, natural products,
composites or at least one combination of these materials.
39. Process according to claim 36, wherein the suspension that
contains at least one inorganic component and at least one metallic
oxide sol, at least one metalloid oxide sol or at least one
composition metallic oxide sol or a mixture of these sols is
produced by suspending at least one inorganic component in at least
one of these sols.
40. Process according to claim 36, wherein the suspension contains
at least one catalytically active component.
41. Process according to claim 36, wherein, the sols are obtained
by hydrolyzing at least one metallic compound, at least one
metalloid compound or at least one composition metallic compound
with one liquid, one gas or one solid.
42. Process according to claim 41, wherein as a liquid, gas or
solid water, water vapor, ice, alcohol or an acid or a combination
of these compounds is used for the hydrolysis of the metallic
compound.
43. Process according to claim 41, wherein the compound to be
hydrolyzed is placed in alcohol or in an acid or a combination of
these liquids before hydrolysis.
44. Process according to claim 41, wherein at least one metal
nitrate, metal chloride, metal carbonate, one metal alcoholate
compound or at least one metalloid alcoholate compound is
hydrolyzed.
45. Process according to claim 44, wherein at least one metal
alcoholate compound or at least one metalloid alcoholate compound
from the alcoholate compounds of the elements Ti, Zr, Al, Si, Sn,
Ce and Y or at least one metal nitrate, metal chloride or metal
carbonate from the metallic salts from the elements Ti, Zr, Al, Si,
Sn, Ce and Y is hydrolyzed.
46. Process according to claim 36, wherein the hydrolysis of the
compounds to be hydrolyzed is carried out with at least half the
molar ratio of water, in relation to the hydrolyzable group of the
hydrolyzable compound.
47. Process according to claim 36, wherein the hydrolyzed compound
is treated with at least one organic or inorganic acid.
48. Process according to claim 47, wherein the organic or inorganic
acid has a concentration of 10 to 60%.
49. Process according to claim 47, wherein the hydrolyzed compound
is treated with at least one mineral acid from the following:
azotic acid, sulfuric acid, perchloric acid and hydrochloric acid
or a combination of these acids.
50. Process according to claim 47, wherein at least one inorganic
component with a particle size of 1 to 10000 nm is suspended in a
sol.
51. Process according to claim 50, wherein an inorganic component
is suspended that contains at least one compound from the
following: metallic compounds, metalloid compounds, composition
metallic compounds or metallic mixture compounds with at least one
element from group III to VII of the periodic system, or at least
one mixture of these compounds.
52. Process according to claim 50, wherein an inorganic component
is suspended that contains at least one compound from the oxides of
the elements of the transition element groups or the elements from
group III to V of the periodic system.
53. Process according to claim 52, wherein the oxides are chosen
from oxides from the elements Sc, Y, Ti, Zr, V, Nb, Cr, Mo, W, Mn,
Fe, Ce, Co, B, Al, In, Tl, Si, Ge, Sn, Pb and Bi.
54. Process according to claim 36, wherein at least one
catalytically active component is added to the sol.
55. Process according to claim 54, wherein at least one
catalytically active component contains at least one compound from
metallic compounds, metalloid compounds, composition metallic
compounds and metallic mixture compounds with at least one element
from group III to VII of the periodic system or organic compounds
or at least one mixture of these compounds.
56. Process according to claim 36, wherein at least one
catalytically active component with a particle size of 1 to 10000
nm is suspended in a sol.
57. Process according to claim 56, wherein at least one
catalytically active component contains at least one compound from
zeolite, silicalite or amorphous mixed oxide systems.
58. Process according to claim 36, wherein the percentage by mass
of the suspended components is 0.1 to 500 times the amount of
hydrolyzed compound used.
59. Process according to claim 36, wherein heating is done by means
of warmed air, hot air, infrared radiation, microwave radiation, or
electrically generated heat.
60. Process according to claim 36, wherein heating is done by means
of using the carrier material as electric resistance heating.
61. Process according to claim 36, wherein stabilization of the
suspension is obtained by applying the suspension onto or into or
onto and into a preheated carrier.
62. Process according to claim 36, wherein at least one carrier is
rolled from a roll and--at a speed of 1 m/h to 1 m/s--runs through
at least one device that applies the suspension onto or into or
onto and into the carrier and through at least one other device
that enables the suspension to be stabilized onto or into or onto
and into the carrier by heating, and wherein the composite produced
in this way is rolled onto a second roll.
63. Process according to claim 36, wherein an unsintered ceramic or
inorganic layer is applied to a carrier and stabilized by being
heated.
64. Process according to claim 36, wherein the dried and stabilized
composite is impregnated with at least one solution containing a
metallic salt, the composite treated in this way is dried by
heating and the metallic salt that is present in and on or in or on
the composite is reduced to a metal.
65. Process according to claim 36, wherein a metallic salt that is
present in the composite is reduced to a metal by treating the
composite with a reducing agent.
66. Process according to claim 66, wherein the reducing agent used
is a hydroboron.
67. Process according to claim 36, wherein a metallic salt that is
present in or on or in and on the composite is reduced to a metal
by using the composite as an electrode in an electrolysis.
68. A process for the separation of material mixtures comprising
filtering material mixtures through the composite of claim 1 to
separate components thereof.
69. A process for the separation of liquid mixtures, gas mixtures,
mixtures containing at least one liquid and at least one gas,
mixtures containing at least one solid and at least one liquid, and
mixtures containing at least one gas and at least one solid or at
least one liquid or one gas comprising filtering said mixtures
through the composite of claim 1 to separate components
thereof.
70. A process for pressurized separation comprising filtering a
mixture of materials under pressure with the composite of claim 1
to separate components thereof.
71. A process for micro-filtration, ultra-filtration or
nano-filtration comprising filtering micro-sized, ultra-sized or
nano-sized particle containing mixtures through a membrane of the
composite of claim 1 to separate the micro-sized, ultra-sized or
nano-sized particles.
72. A process comprising carrying out a catalytic process with the
composite of claim 1.
73. A process comprising carrying out a catalytic process with the
composite according to claim 1 as a catalyst carrier, whereby an
electric field is connected to the catalyst carrier and the
catalyst carrier is connected as an anode or a cathode.
74. A process comprising carrying out a catalytic process with the
composite according to claim 1 as a catalyst membrane, whereby the
catalytic effect of oxygen-ion conducting electrolytes is used that
ensues with the oxygen-ion conduction in the electric field.
75. A process comprising carrying out a catalytic process with the
composite according to claim 1 as a carrier material for the
production of a catalytically active, permeable composite.
76. Catalytically active permeable flexible composite based on at
least one perforated and permeable carrier, which contains on at
least one side of the carrier and inside the carrier at least one
inorganic component, which consists essentially of at least one
compound of a metal, a metalloid or a composition metal and at
least one element from group III to VII of the periodic system,
which permeable flexible composite is obtained by application of a
suspension, which contains said at least one inorganic component
and a sol, on and inside at least one flexible, perforated and
permeable carrier, and stabilizing the suspension by heating the
suspension at least once either at a temperature of between 50 and
100.degree. C. for 10 minutes to 5 hours, or at a temperature of
between 100 and 800.degree. C. for 1 second to 10 minutes,
wherein said composite has a total thickness of not less than about
5 .mu.m and not more than about 150 .mu.m.
Description
A claim is laid to a catalytically active, permeable composite, a
process of production and use of this permeable composite.
There are several different applications known where composites
containing ceramic materials are used.
The advantage of composites containing ceramic material is in the
fact that ceramic coatings are chemically inert against most
chemical substances such as organic substances and besides this are
generally resistant to acids or caustic solutions. For this reason
metals are often coated with ceramic materials in order to protect
the metal from chemical attack. In addition to this, the porous
surface of a composite coated with a ceramic material increases the
abrasion resistance of paints or protective coatings that are
applied at a later date. Because of their porous surface. ceramic
materials themselves are very suitable for use as membranes or
filters.
The disadvantage of ceramic materials or composites containing
ceramic materials is the brittleness of the ceramic material.
Metals coated with ceramic material are therefore very susceptible
to shocks, and the ceramic coating, rarely survives mechanical
stresses without the surface of the ceramic material being damaged.
Since bending such a ceramic composite also damages the ceramic
coating, the fields of application of such ceramic composites are
limited at the present time
In spite of the disadvantages, ceramic composites are often used in
filtration and membrane technology.
EP 0358 338 describes a process in which an aqueous solution
containing a metallic oxide sol is applied to and stabilized on
a--preferably smooth metallic--surface, thus protecting this
surface with a ceramic coating. To improve the bond between the
ceramic coating and the surface to be protected a metallic oxide
powder and/or a bond-improving agent can be added to the aqueous
solution. The process does not describe the coating of permeable
carrier materials.
WO 96/00198 shows the production of ceramic coatings on surfaces
made from different materials. These coated materials can be used
as membranes in micro-filtration. In this process, titanium dioxide
sol is dispersed with aluminum oxide powder, whereby hydrochloric
acid is used as a peptizing agent,
U.S. Pat. No. 4,934,139 shows a process for the production of
ceramic membranes for ultra-filtration and micro-filtration. For
the production of such ceramic membranes a sol or a particle
suspension is applied to a metallic carrier and sintered. The
porous carrier can be stainless-steel-sintered metal or stainless
steel mesh where metallic particles have been sintered into the
gaps. Metallic mesh with gaps of more than 100 .mu.m cannot be
produced using this process without sintering in metallic
particles. The process prevents the suspension or the sol from
penetrating the gaps in the carrier material.
In U.S. Pat. Nos. 5,376,442 and 5,605,628, an organic bonding agent
is worked into the coating solution to bridge the gaps in the
carrier material. This bonding agent must be removed again during
stabilization, which can lead to irregularities in the ceramic
material surface and/or structure.
With the above-mentioned processes it is not possible to produce
catalytically active composites containing ceramic material, where
ceramic material is contained in and on the carrier material,
without the ceramic coating being damaged during production.
The basis of the invention at issue is therefore to make available
a catalytically active composite that contains ceramic components
on and in the carrier and to find a simple and economic process of
producing such a composite.
Surprisingly, it was found to be the case that a catalytically
active, permeable composite based on at least one perforated and
permeable carrier containing at least one inorganic component on at
least one side of the carrier and inside the carrier, which
essentially contains a compound consisting of a metal and at least
one element from group III to VII of the periodic system, can be
produced simply and at a reasonable price.
Subject matter of the invention at issue is therefore a
catalytically active, permeable composite based on at least one
perforated and permeable carrier containing at least one inorganic
component on at least one side of the carrier and inside the
carrier, which essentially contains a compound consisting of a
metal and at least one element from group III to VII of the
periodic system.
Further subject matter of the invention at issue is a catalytically
active, permeable composite, which is obtained by application of a
suspension that contains at least one inorganic compound, which is
a compound of at least one metal with at least one element from
group III to VII of the periodic system, and a sol on a perforated
and permeable carrier, which is then heated at least once to
stabilize the suspension containing at least one inorganic
component onto or into or onto and into the carrier.
Further subject matter of the invention at issue is a process to
produce a catalytically active, permeable composite as claimed in
one of claims 1 to 36, wherein at least one suspension, which
contains at least one inorganic component from at least one
compound of at least one metal with at least one of the elements of
group III to VII of the periodic system, is applied in and on at
least one perforated and permeable carrier, and is stabilized in or
on or in and on the carrier material when the suspension is
subsequently heated at least once.
Subject matter of the invention at issue is furthermore the use of
a composite according to at least one of the claims 1 to 36 as a
filter to separate mixtures.
Permeable composites or carriers respectively are materials that
are permeable for substances with a particle size of between 0.5 nm
and 500 .mu.m, depending on the style of execution of the composite
or carrier respectively. The substances can be gaseous, liquid or
solid or in a mixture of these states of aggregation.
The composite according to invention has the advantage that
inorganic components can be stabilized on and in a perforated and
permeable carrier, which allow this composite to be permeable and
catalytically active, without the coating being damaged during
production.
The composite according to invention also has the advantage that,
although it partly consists of a ceramic material, it can be bent
to a radius of up to 1 mm. This property enables an especially
simple process of producing this composite, as the composite
created by coating with a ceramic material can be wound on or off a
roll. Furthermore, this property enables the adaptation of the
composite according to invention to various module shapes such as,
for example, spiral modules, flat modules or pocket modules when
used as a membrane.
The process of producing the composite according to invention also
has the advantage that carriers with perforated surfaces with a
maximum gap size of 500 .mu.m can be coated. The especially careful
conditions during stabilization of the suspension in or on the
carrier enable carrier materials to be used that cannot be
subjected to high temperatures or only subjected to high
temperatures for a very short time.
The catalytically active composite according to invention, which is
produced according to the process that is the subject of the
invention, is ideally suited for use as a filter, catalyst, or
membrane. The possibility of also being able to use carriers that
have gaps with a size of up to 500 .mu.m allows the use of
exceptionally reasonably priced materials. The particle size used
in combination with the gap size of the carrier material used
allows the pore size and/or the pore size distribution to be easily
adjusted in the composite so that special, catalytically active
membranes can be produced for special applications. Some of these
applications cannot be carried out without the composite according
to invention.
The catalytically active composite according to invention is
described in the following as an example, without the composite
according to invention being limited to this style of
execution.
The catalytically active, permeable composite according to
invention has a basis of at least one perforated and permeable
carrier. On at least one side of the carrier and inside the
carrier, the carrier contains at least one inorganic component that
contains essentially at least one compound consisting of at least
one metal, metalloid or composition metal with at least one element
from group III to VII of the periodic system. The inside of a
carrier in the invention at issue means hollows or pores in a
carrier.
The catalytically active, permeable composite according to
invention can be obtained by the application of a suspension
containing at least one inorganic component, which contains a
compound of at least one metal, metalloid, or composition metal
with at least one element from group III to VII of the periodic
system, and a sol onto a perforated and permeable carrier, which is
subsequently heated at least once to stabilize the suspension
containing at least one inorganic component on or in or on and in
the carrier.
However, according to invention, the catalytically active,
permeable composite can also be obtained by chemical vapor
deposition, impregnation, or co-precipitation.
According to invention, the composite can be permeable for gases,
solids, or liquids, especially for particles with a size of between
0.5 nm and 10 .mu.m.
The gaps can be pores, mesh, holes, crystal lattice gaps or
hollows. The carrier can contain at least one material from the
following: carbon, metals, alloys, glass, ceramic materials,
minerals, plastics, amorphous substances, natural products,
composites or at least one combination of these materials. The
carriers, which can contain the above-mentioned materials, could
have been modified by a chemical, thermal, or mechanical treatment
or a combination of treatments. The composite preferably contains a
carrier, which contains at least one metal, a natural fiber or a
plastic, which has been modified by at least one mechanical
deformation or treatment technology respectively, such as drawing,
swaging, flex-leveling, milling, stretching, or forging. It is
absolutely preferable that the composite contains at least one
carrier, that has at least woven, glued, felted or ceramically
bound fibers or at least sintered or glued formed bodies, spheres
or particles. In another preferred construction, a perforated
carrier can be used. Permeable carriers can also be carriers that
become or were made permeable by laser or ion beam treatment.
It can be advantageous, if the carrier contains fibers from at
least one of the following materials: carbon, metals, alloys,
ceramic materials, glass, minerals, plastics, amorphous substances,
natural products, composites or fibers consisting of at least one
combination of these materials, such as asbestos, glass fibers,
rock wool fibers, carbon fibers, metal wires, steel wires,
polyamide fibers, coconut fibers, coated fibers. Preferably
carriers are used that at least contain woven fibers made of metal
or alloys. Metal fibers can also be wires. Especially preferable is
a composite containing a carrier that has at least one mesh made of
steel or stainless steel, such as, for example, steel wire, steel
fibers, stainless steel wire, or stainless steel fiber meshes
produced by weaving. The preferable mesh size is between 5 and 500
.mu.m, the especially preferred mesh size is between 50 and 500
.mu.m and the very specially preferred mesh size is between 70 and
120 .mu.m.
However, the composite carrier can also have at least one expanded
metal with a pore size of between 5 and 500 .mu.m. According to
invention, the carrier can also have at least one granular sintered
metal, one sintered glass or one metal web with a pore width of
between 0.1 .mu.m and 500 .mu.m, preferably between 3 and 60
.mu.m.
The composite according to invention preferably has at least one
carrier that has at least one of the following: aluminum, silicium,
cobalt, manganese, zinc, vanadium, molybdenum, indium, lead,
bismuth, silver, gold, nickel, copper, iron, titanium, platinum,
stainless steel, steel, brass, an alloy of these materials or a
material coated with Au, Ag, Pb, Ti, Ni, Cr, Pt, Pd, Rh, Ru and/or
Ti.
The inorganic component contained in the composite according to
invention can contain at least one compound of at least one metal,
metalloid or composition metal with at least one element from group
III to VII of the periodic system or at least one mixture of these
compounds. Moreover, the compounds of metals, metalloids or
composition metals can contain at least elements of the
transitional element groups and of group III to V of the periodic
system or at least elements of the transitional element groups or
of group III to V of the periodic system, whereby these compounds
have a particle size of between 0.001 and 25 .mu.m. Preferably the
inorganic component contains at least one compound of an element of
group III to VII of the transitional element groups or at least one
element of group III to V of the periodic system with at least one
of the elements Te, Se, S, O, Sb, As, P, N, Ge, Si, C, Ga, Al or B
or at least one compound of an element of group III to VIII of the
transitional element groups and at least one element of group III
to V of the periodic system with at least one of the elements Te,
Se, S, O, Sb, As, P, N, Ge, Si, C, Ga, Al or B or a mixture of
these compounds. It is especially preferred if the inorganic
component contains at least one compound of at least one of the
elements Sc, Y, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Fe, Co, B, Al, Ga,
In, Tl, Si, Ge, Sn, Pb, Sb or Bi with at least one of the elements
Te, Se, S, O, Sb, As, P, N, C, Si, Ge or Ga, such as, for example.
TiO.sub.2, Al.sub.2 O.sub.3, SiO.sub.2, ZrO.sub.2, Y.sub.2 O.sub.3,
BC, SiC, Fe.sub.3 O.sub.4, SiN, SiP, nitrides, sulfates,
phosphides, silicides, spinels or yttrium aluminum garnet, or one
of these elements itself. The inorganic component can also have
alumosilicates, aluminumphosphates, zeolites or partially
substituted zeolites, such as, for example, ZSM-5, Na-ZSM-5 or
Fe-ZSM-5 or amorphous microporous mixed oxide systems, which can
contain up to 20% non-hydrolyzable organic compounds, such as, for
example, vanadium oxide-silicium oxide-glass or aluminum
oxide-silicium oxide-methyl silicium sesquioxide-glasses.
Preferably there is at least one inorganic component in a particle
size fraction with a particle size of between 1 and 250 nm or with
a particle size of between 260 and 10000 nm.
It can be advantageous if the composite according to invention has
at least two particle size fractions of at least one inorganic
component. The particle size proportion of the particle size
fractions in the composite can be between 1:1 and 1:10000,
preferably between 1:1 and 1:100. The proportion of ingredients of
the particle size fraction in the composite can preferably be
between 0.01:1 and 1:0.01.
The permeability of the composite according to invention can be
limited by the particle size of the inorganic component used to
particles with a certain maximum size.
The suspension containing at least one inorganic component, which
allows the composite according to invention to be obtained, can
contain at least one liquid from the following: water, alcohol and
acid or a combination of these liquids.
The composite according to invention contains at least one
catalytically active component. The catalytically active component
can be identical to the inorganic component. This especially
applies when the inorganic component has catalytically active
centers on the surface.
For a catalytically active component, the composite according to
invention preferably contains at least one inorganic material, at
least one metal or at least one organo-metallic compound, which has
catalytically active centers on its surface. It is especially
preferable if the composite has a zeolite as a catalytic component,
such as, for example, ZSM-5, Fe-ZSM-5, silicalite or an amorphous
microporous mixed oxide, as, for example, described in DE 195 45
042 and/or DE 195 06 843, such as, for example, vanadium
oxide-silicium oxide-glass or aluminum oxide-silicium oxide-methyl
silicium sesquioxide-glasses.
However, as a catalytically active component, the composite can
contain have at least one oxide of at least one of the elements Mo,
Sn, Zn, V, Mn, Fe, Co, Ni, As, Sb, Pb, Bi, Ru, Re, Cr, W, Nb, Hf,
La, Ce, Gd, Ga, In, Tl, Ag, Cu, Li, K, Na, Be, Mg, Ca, Sr and
Ba.
In a special style of execution of the catalytically active,
permeable composite according to invention, this contains at least
titanium suboxide.
It can also be advantageous if the composite has at least one metal
compound from the compounds of the metals Pt, Rh, Ru, Ir, Au, Ag,
Os, Re, Cu, Ni, Pd and Co or at least one metal from the metals Pt,
Rh, Ru, Ir, Au, Ag, Os, Re, Cu, Ni, Pd and Co as a catalytic
component.
In an especially preferred style of execution of the composite
according to invention, this composite can be constructed in such a
way that it can be bent without the inorganic components stabilized
on the inside of the carrier and on the carrier being destroyed.
The composite according to invention is preferably flexible to a
smallest radius of up to 1 mm.
The process according to invention for the production of a
composite according to invention is described in the following as
an example without being limited to this example.
In the process according to invention for the production of the
composite according to invention, at least one suspension
containing at least one inorganic component consisting of at least
one compound of one metal, metalloid or composition metal with at
least one element from group III. to VII of the periodic system and
one sol is applied into and/or onto at least one perforated and
permeable carrier. The suspension is stabilized on or in or on and
in the carrier material by being heated at least once.
When implementing the process according to invention it could be
advantageous to apply the suspension onto and into or onto or into
at least one carrier by stamping on, pressing on or in, rolling on,
applying with a blade or a brush, dipping, spraying or pouring.
The perforated and permeable carrier can contain at least one of
the following materials: carbon, metals, alloys, glass, ceramic
materials, minerals, plastics, amorphous substances, natural
products, composites or at least one combination of these
materials.
The suspension used, which can contain at least one inorganic
component and at least one metallic oxide sol, at least one
metalloid oxide sol or at least one composition metallic oxide sol
or a mixture of these sols, can be produced by suspending at least
one inorganic component in at least one of these sols. It can be
advantageous if the suspension has at least one catalytically
active component. The catalytically active component can be
identical to the inorganic component.
The sols are obtained by hydrolyzing at least one metallic
compound, at least one metalloid compound or at least one
composition metallic compound with one liquid, one gas or one
solid, whereby it can be advantageous if as a liquid for hydrolysis
of the compound to be hydrolized water, alcohol or an acid or a
combination of these liquids or as a solid ice or as a gas water
vapor is used. It could also be advantageous to place the compound
to be hydrolyzed in at least one alcohol or at least one acid or a
combination of these liquids before hydrolysis. As a compound to be
hydrolyzed it is preferable to hydrolyze at least one metal
nitrate, one metal chloride, one metal carbonate, one metal
alcoholate compound or at least one metalloid alcoholate compound.
Especially preferable is at least one metal alcoholate compound,
one metal nitrate, one metal chloride, one metal carbonate or at
least one metalloid alcoholate compound from compounds of the
elements Ti, Zr, Al, Si, Sn, Ce and Y or the lanthanides and
actinides, such as, for example, titanium alcoholates, such as, for
example, titanium isopropylate, silicium alcoholates, zirconium
alcoholates, or a metallic nitrate, such as, for example, zirconium
nitrate.
It can be advantageous to carry out the hydrolysis of the compounds
to be hydrolyzed with at least half the mol ratio water, water
vapor or ice in relation to the hydrolyzable group of the
hydrolyzable compound.
For peptizing, the hydrolyzed compound can be treated with at least
one organic or inorganic acid, preferably with a 10 to 60% organic
or inorganic acid, especially preferred with a mineral acid from
the following: sulfuric acid, hydrochloric acid, perchloric acid,
phosphoric acid and azotic acid or a mixture of these acids.
Not only sols produced as described above can be used, but also
commercially available sols such as titanium nitrate sol, zirconium
nitrate sol or silica sol.
It can be advantageous if at least one inorganic component having a
particle size of between 1 and 10000 nm is suspended in at least
one sol. Preferably an inorganic component is suspended containing
at least one compound from the following: metallic compounds,
metalloid compounds, composition metallic compounds and metallic
mixture compounds with at least one of the elements from group III
to VI of the periodic system or at least a mixture of these
compounds. It is especially preferred if at least one inorganic
component is suspended, which contains at least one compound from
the oxides of the transition element groups or from the elements of
group III to V of the periodic system, preferably oxides from the
following elements: Sc, Y, Ti, Zr, Nb, Ce, V, Cr, Mo, W, Mn, Fe,
Co, B, Al, In, Tl, Si, Ge, Sn, Pb and Bi, such as, for example,
Y.sub.2 O.sub.3, ZrO.sub.2, Fe.sub.2 O.sub.3, Fe.sub.3 O.sub.4,
SiO.sub.2, Al.sub.2 O.sub.3.
Preferably the percentage by mass of the suspended component should
be 0.1 to 500 times the hydrolyzed compound used.
It can be advantageous if at least one catalytically active
component is added to the sol.
It can also be advantageous if at least one catalytically active
component, which has a particle size of 1 to 10000 nm, is suspended
in a sol. Preferably at least one catalytically active component is
suspended, which has at least one compound chosen from metallic
compounds, metalloid compounds, composition metallic compounds and
metal mixture compounds with at least one element of group III to
VII of the periodic system or organic compounds or at least a
mixture of these compounds. Especially preferred for suspension is
at least one catalytically active component, which contains at
least one compound from alumosilicates, aluminumphosphates,
zeolites or partially substituted zeolites, such as, for example,
ZSM-5, Na-ZSM-5 or Fe-ZSM-5 or amorphous microporous mixed oxide
systems, which can contain up to 20% non-hydrolyzable organic
compounds such as, for example, vanadium oxide-silicium oxide-glass
or aluminum oxide-silicium oxide-methyl silicium
sesquioxide-glasses.
Preferably the percentage by mass of the suspended component should
be 0.1 to 500 times the hydrolyzed compound used.
The fracture resistance in the composite according to invention can
be optimized by a suitable choice of the particle size of the
suspended compounds in dependence on the size of the pores, holes
or gaps of the perforated permeable carrier, but also by the layer
thickness of the composite according to invention as well as by the
proportional ratio of sol, solvent and metallic oxide.
When using a mesh with a mesh width of, for example, 100 .mu.m, the
fracture resistance can be increased by the preferable use of
suspensions containing a suspended compound with a particle size of
at least 0.7 .mu.m. In general, the ratio of particle size to mesh
or pore size respectively should be between 1:1000 and 50:1000. The
composite according to invention can preferably have a thickness of
between 5 and 1000 .mu.m, especially preferable is a thickness of
between 50 and 150 .mu.m. The suspension consisting of sol and
compounds to be suspended preferably has a ratio of sol to
compounds to be suspended of 0.1:100 to 100:0.1, preferably of
0.1:10 to 10:0.1 parts by weight.
According to invention, the suspension that is present on or in or
on and in the carrier can be stabilized by heating this composite
to between 50 and 1000.degree. C., In a special variant, the
composite is subjected to a temperature of between 50 and
100.degree. C. for 10 minutes to 5 hours. In a further special
style of execution, the composite is subjected to a temperature of
between 100 and 800.degree. C. for 1 second to 10 minutes.
Heating the composite according to invention can be carried out by
means of warmed air, hot air, infrared radiation, microwave
radiation, or electrically generated heat. In a special style of
execution of the process according to invention it can be
advantageous if heating of the composite is carried out using the
carrier material as electric resistance heating. For this purpose,
the carrier can be connected to an electrical power source by at
least two contacts. Depending on the strength of the power source,
voltage released, and inherent resistance of the conductive
carrier, the carrier heats up when the power is switched on, and
the suspension that is present in and on the surface of the carrier
can thus be stabilized.
In a further preferred style of execution of the process according
to invention stabilization of the suspension can be achieved by
applying the suspension onto or into or onto and into a preheated
carrier thus stabilizing it immediately upon application.
In a further special style of execution of the process according to
invention it can be advantageous that at least one carrier is
rolled from a roll and--at a speed of between 1 m/h and 1 m/s--runs
through at least one device that applies the suspension onto or
into or onto and into the carrier and through at least one other
device that enables the suspension to be stabilized onto or into or
onto and into the carrier by heating, and that the composite
produced in this way is rolled onto a second roll. In this way it
is possible to produce the composite according to invention in a
continuous process.
In a further special style of execution of the process according to
invention it can be advantageous, if a ceramic or an inorganic
layer is applied to the carrier, which can be a composite, a
composite according to invention or a composite produced by the
process according to invention. To this purpose, a green
(unsintered) layer of ceramic material or an inorganic layer, for
example, which can, for example, be on an auxiliary film, can be
laminated onto the carrier or the composite treated with another
suspension as described above. This composite can be stabilized by
heating, for example, by infrared radiation or in a kiln.
The green ceramic material layer that is used preferably contains
nanocrystalline powder from at least one metalloid oxide or
metallic oxide, such as, for example, aluminum oxide, titanium
dioxide or zirconium dioxide. The green layer can also contain an
organic bonding agent.
By using a green ceramic material layer it is a simple matter to
provide the composite according to invention with an additional
ceramic layer, which--according to the size of the nanocrystalline
powder used--limits the permeability of the composite produced in
this way to smallest particles.
Preferably, the green layer of nanocrystalline powder has a
particle size of between 1 and 1000 nm. If nanocrystalline powder
with particle sizes of between 1 and 10 nm is used, the composite
according to invention, onto which an additional ceramic layer has
been applied, has a permeability for particles with a size
corresponding to the particle size of the powder that was used. If
nanocrystalline powder with a size of more than 10 nm is used, the
ceramic layer is permeable for particles that are half as large as
the particles of the nanocrystalline powder that was used.
By applying at least one other inorganic or ceramic material layer
according to invention, a composite according to invention is
obtained that has a pore gradient. To produced composites with a
defined pore size, it is also possible to use carriers, whose pore
or mesh size respectively is not suitable for the production of a
composite with the required pore size, if several layers are
applied. This can, for example, be the case when a composite with a
pore size of 0.25 .mu.m is to be produced using a carrier with a
mesh width of more than 300 .mu.m. To obtain such a composite it
can be advantageous to apply at least one suspension on the
carrier, which is suitable for treating carriers with a mesh width
of 300 .mu.m, and stabilizing this suspension after application.
The composite obtained in this way can then be used as a carrier
with a smaller mesh or pore size respectively. Another suspension,
for example, that contains, for example, a compound with a particle
size of 0.5 .mu.m can be applied to this carrier.
The fracture indifference of composites with large mesh or pore
widths respectively can also be improved by applying suspensions to
the carrier that contain at least two suspended compounds.
Preferably, suspended compounds are used that have a particle size
ratio of 1:1 to 1:10, especially preferred is a ratio of between
1:1.5 and 1:2.5. The proportion by weight of the particle size
fraction with the smaller particle size should not exceed a
proportion of 50% at the most, preferably 20% and especially
preferably 10% of the total weight of the particle size
fraction.
In spite of an additional layer of ceramic material or inorganic
material, which can contain catalytically active components, being
applied to the carrier, the composite according to invention can be
flexible.
The composite according to invention can also be produced by
placing a carrier, that can be, for example, a composite according
to invention or another suitable carrier material, onto a second
carrier that can be the same material as the first carrier or
another material or two carriers of different permeability or
porosity respectively. A spacer, a drainage material or another
material suitable for material conduction, for example, a mesh
composite, can be placed between the two carrier materials. The
edges of both carriers are connected to each other by various
processes, for example, soldering, welding or adhering. Adhering
can be done with commercially available bonding agents or adhesive
tape. The suspension can then be applied to the carrier composite
that has been produced in the above-mentioned ways.
In an especially preferred style of execution, the two carriers
placed on top of each other with at least one spacer, drainage
material or similar material placed between them, can be rolled up
before or after joining the edges of the carrier, but preferably
after joining. By using thicker or thinner adhesive tape to join
the edges of the carrier, the space between the two carrier
composites that are placed on top of each other can be influenced
during rolling. A suspension as described above can be applied to
such carrier composites that have been rolled up in this way, for
example, by dipping in a suspension. After dipping, the carrier
composite can be freed of surplus suspension with the aid of
compressed air. The suspension that has been applied to the carrier
composite can be stabilized in the above-mentioned manner. A
composite produced in the above-mentioned manner can be used in a
wound module as a form-selective membrane.
In another special style of execution of the process according to
invention, the above-mentioned carrier composite can also be
produced when two carriers and, if intended, at least one spacer
are rolled from one roll and then placed on top of each other. The
edges can again be joined by soldering, welding or adhesion or
other suitable processes of joining flat bodies. The suspension can
then be applied to the carrier composite produced in this manner.
This can be done, for example, by the carrier composite being
sprayed or painted with the suspension or the carrier composite
being drawn through a bath containing the suspension. The applied
suspension is stabilized according to one of the above-mentioned
processes. The composite produced in this way can be wound onto a
roll. Another inorganic layer can be applied into and/or onto such
a material by a further application and stabilization of a further
suspension. Using different suspensions allows the material
properties to be adjusted according to wish or intended use
respectively. Not only further suspensions can be applied to these
composites, but also unsintered ceramic and/or inorganic layers,
which are obtainable by lamination in the above-mentioned way. The
described style of execution of the process according to invention
can be carried out continuously or intermittently, preferably
continuously. A composite produced in this way can be used as a
form-selective membrane in a flat module.
The carrier in the composite can, depending on the carrier
material, be removed again thus creating a ceramic material that
has no further trace of carrier material. For example, if the
carrier is a natural material such as a cotton fleece, this can be
removed from the composite in a suitable reactor by oxidation. If
the carrier material is a metal, such as, for example, iron, this
carrier can be dissolved by treating the composite with acid,
preferably with concentrated hydrochloric acid. If the composite
was also made from zeolite, flat zeolite bodies can be produced
that are suitable for form-selective catalysis
It can be advantageous to use the composite according to invention
as a carrier for the production of a composite according to
invention.
In a special style of execution of the process according to
invention, the dried and stabilized composite can be treated with a
solution containing at least one metallic compound, preferably a
metallic salt such as RhCl.sub.3, after the stabilization of the
suspension or ceramic or inorganic layer on and/or in the carrier
material. This treatment can, for example, consist of spraying,
squirting, painting or rolling the solution containing a metallic
compound onto the composite or, for example, by dipping the
composite into a solution containing a metallic compound. The
composite treated in such a way is dried by heating. Heating can
take place as described above. The metallic compound, which is
present in and on or in or on the composite after application and
drying, is reduced to a metal.
It can be advantageous to reduce the metallic compound present in
and/or on the composite to a metal with the help of a reduction
agent, preferably with a hydroboron and especially preferably with
NaBEt.sub.3 H, LiBEt.sub.3 H, NaBMe.sub.3 H or KBPr.sub.3 H.
Preferably the composite according to invention, which contains
metallic compounds that are to be reduced, is treated with an
organic solvent that contains at least one of the
hydroorganoborates. Since the salts created form well soluble
complexes with the bororganic complexing agents in an organic
phase, the composite according to invention is kept virtually free
of boron. If the composite contains several metallic salts, then
particles can be obtained after reduction, which are true alloys
consisting of at least two metals, such as, for example,
rhodium-platinum, iron-cobalt-nickel or palladium-platinum
alloys.
For compounds to be reduced, metallic compounds from the following
can be used: nitrates, halogenides, hydroxides, cyanides,
thiocyanides or alcoholates of the metals chromium, manganese,
iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium,
silver, osmium, iridium, platinum, zinc, cadmium, rhenium or gold
or mixtures of these metals or compounds. These compounds can be
added to the suspension during the production of the composite
according to intention or can be applied after the stabilization of
a suspension according to invention on a carrier.
It can also be advantageous to reduce a metallic compound present
on or in or on and in the composite to a metal by using the
composite as an electrode in an electrolysis.
Catalytically active metals can also be applied into and/or onto
the composite by using a composite according to invention without a
catalytically active component as an electrode for electrolysis of
a precious metalsaliferous solution. In this case it is necessary
that the composite contains at least TiO.sub.2 as an inorganic
component and at least one partially electrically conductive
carrier. By connecting a voltage of 2 to 3 volts, the composite
becomes electrically conductive because titanium suboxide is
formed, which is electrically conductive. Due to the electrolysis,
catalytically active precious metal is deposited in and/or on the
composite, preferably in very fine particles.
It can be advantageous to use the composite according to invention
as a filter to separate material mixtures. It is especially
preferable to use the composite according to invention as a filter
for separating liquid mixtures, gas mixtures, mixtures containing
at least one liquid and at least one gas, mixtures containing at
least one solid and at least one liquid, and mixtures containing at
least one gas and at least one solid or at least one liquid or one
gas. The composite can also be used as a filter in pressurized
separation processes.
It is especially advantageous to use a composite according to
invention as a membrane for micro-filtration. ultra-filtration or
nano-filtration.
It can also be advantageous to use a composite according to
invention in catalytic processes. It can be especially advantageous
to use the composite as a catalyst carrier, whereby the catalyst
carrier has an electric field connected to it and the catalyst
carrier is connected as an anode or cathode. The composite can also
be used as a catalyst membrane, whereby the catalytic effect of
oxygen-ion conductive solid electrolytes is used, which ensues in
the oxygen-ion conduction in the electrical field.
If it contains at least one titanium dioxide, the composite
according to invention can be used as a catalytically effective
membrane or as a catalyst, when by connection to an electrical
field a non-stoichiometric titanium-dioxide compound is formed.
By connecting the composite as a cathode, the catalytically
reductive effect of the composite can be used. By connecting the
composite as an anode, the catalytically oxidative effect of the
composite can be used.
It is especially preferable to use the composite according to
invention for the catalytic conversion of oxygenous compounds. The
composite according to invention can, for example, be used for the
reduction of nitrate or nitrite ions in waste water or, for
example, for the degradation of ozone in oxygen.
It is especially preferable to use the composite according to
invention for oxidation reactions. If SO.sub.2 and oxygen are
conducted through a composite according to invention, which, for
example, contains at least V.sub.2 O.sub.5, the catalytically
active composite converts SO.sub.2 into SO.sub.3, which can be
washed out of a gas containing SO.sub.2. It is also possible to
oxidize organic compounds by means of the catalytically active
composite, for example, aromatic compounds into hydroxy aromatic
compounds.
It is also possible to use the composite according to invention as
a carrier for the preparation of a composite according to
invention.
It can be advantageous to combine preferred styles of execution of
the process according to invention with at least one other
preferred style of execution of process according to invention. It
can also be advantageous to combine preferred styles of execution
of the composite according to invention with at least one other
special style of execution or form of the composite according to
invention. Further styles of execution of the process according to
invention, of the composite according to invention and/or further
possibilities for using the process according to invention or
composite according to invention are opened up to the specialist
with knowledge of the invention at issue.
The catalytically active composite, processes for its production
and the use of the composite according to invention are described
in the following examples without being limited to these
examples.
EXAMPLE 1.1
A suspension consisting of 25 g titanium isopropylate was
hydrolyzed with 12 g water. The resulting precipitation was
subsequently peptized with approx. 35 g azotic acid (25%), and
after this was completely dissolved, 10 g titanium dioxide (30 nm;
type P25, Degussa) and 3 g titanium dioxide in its anatase form
were added, and the suspension was stirred until all agglomerates
were completely dissolved. This suspension was applied to a
thickness of 20 .mu.m to a permeable ceramic composite with an
average pore width of 0.4 .mu.m. After drying and stabilization of
the composite by subjecting the composite to a temperature of
450.degree. C. for 2 seconds, the catalytically active composite
could be used for photochemical catalytic oxidation reactions. By
rolling up the composite and placing the composite in a tubular
reactor that has a UV radiator in its center, the effectiveness of
the UV radiator (quantum yield, conversion) for the degradation of
TOC could be increased enormously.
EXAMPLE 1.2
A permeable composite, as can be obtained by applying a sol of 120
g titanium triisopropylate, 60 g water, 100 g hydrochloric acid
(25%) and 280 g aluminum oxide (SC530SG, Alcoa) onto a carrier
consisting of a square mesh with a mesh width of 150 .mu.m, was
dipped into a solution of 50 g potassium permanganate in 1000 ml
water and subsequently dried in a hot airflow at 450.degree. C.
During this process, manganese dioxide, which can degrade ozone
catalytically, is formed in the pores of the carrier. This
catalytically active, permeable composite is used for the catalytic
elimination of ozone from the air sucked in by automobiles.
EXAMPLE 1.3
120 g titanium tetraisopropylate was mixed with 140 g de-ionized
ice and stirred vigorously until the resulting precipitation was
finely dispersed. After adding 100 g of 25% hydrochloric acid, the
mixture was stirred until it became clear. 9 g FeCl.sub.3 and 3 g
CoCl.sub.2 as well as 280 g .alpha.-aluminum oxide type CT3000SG
from Alcoa, Germany, were added and stirred vigorously for several
days until all the aggregates are dissolved.
The suspension thus obtained was painted in a layer onto a nickel
rib mesh with 90 .mu.m grid width to a thickness of approx. 30-150
.mu.m and stabilized by means of a hot-air drier at 100-150.degree.
C. within 10 minutes. During this process, a composite is obtained,
which has a mechanically solid, ceramic coating. The
macro-structure of this ceramic material consists of
.alpha.-aluminum oxide and has a pore width of 0.45 .mu.m. On the
surfaces of the aluminum oxide particles there are ceramic
membranes as a micro-structure, which are only a few micrometers
thin. The metallic salts are in the structure and pores of the
macro-structure.
The composite was rolled up in a pipe, put in a solution of 150 ml
1.7 molar solution of LiBEt.sub.3 H in THF and left there for 10
hours. Subsequently, the composite was taken out of the solution
and then first washed with 800 ml THF, then with 1500 ml ethanol
and then with a mixture of 800 ml ethanol and 800 ml THF till
degassing was over.
EXAMPLE 1.4
In an experiment that was conducted as under example 1.3, a mesh of
stainless steel (VA-steel) was used instead of nickel rib mesh. So
that this mesh would not be destroyed by chloride ions, nitrates of
cobalt and iron were used instead of chlorides and as an acid 140 g
of 54% azotic acid was used.
EXAMPLE 1.5
A suspension of 30 g titanium tetraisopropylate was hydrolyzed with
60 g water and subsequently peptized with 45 g sulfuric acid (20%).
Subsequently, 90 g aluminum oxide (A16SG, Alcoa) was added and
stirred until the agglomerates were completely dissolved. This
suspension was applied to a rib mesh with an average mesh width of
50 .mu.m and dried and stabilized at 450.degree. C. within 2
seconds.
The composite obtained in this way was used as an electrode
membrane in electrolysis. When feeding an electrical voltage of
approx. 2.5 volts to the electrode membrane, which was placed in a
precious metal solution, an electrolytic precipitation of the
precious metal took place in the pores of the composite. This is
only possible by using titanium dioxide as an inorganic component
in the composite, since by formation of titanium suboxide at a
voltage of more than 2 volts this titanium suboxide becomes
electrically conductive. Graphite electrodes were used as a counter
electrode. In this way almost all known precious metal catalysts
and precious metal catalyst systems (such as, for example, Pt/Rh,
Pt/Pd or Pt/lr) can be precipitated.
EXAMPLE 1.6
A suspension of 30 g titanium tetraisopropylate was hydrolyzed with
60 g water and then peptized with 45 g azotic acid (25%).
Subsequently, 30 g titanium dioxide (P25, Degussa) was added and
stirred until the agglomerates were completely dissolved. This
suspension was applied to a titanium wire netting with an average
mesh width of 80 .mu.m and dried and stabilized at 450.degree. C.
within 2 seconds. If the composite obtained in this way is
connected as a cathode and dipped with a graphite anode into a
solution of 1% azotic acid in water, the nitrate is almost
completely decomposed within 10 hours at a voltage of 2.1 volts and
a current efficiency of 20%.
The composite according to invention is thus well suited for the
reduction of nitrate compounds, especially for nitrate degradation
in aqueous systems.
EXAMPLE 1.7
If the composite produced according to example 1.6 is connected as
a cathode and dipped into a
sodium-palladium-tetrachloride/copper-dichloride solution, the
palladiun/copper catalyst precipitates at 2V in a fine dispersion
on the surface of the composite. If the composite produced in such
a way and equipped with a catalyst, again connected as a cathode,
is dipped with a graphite anode into a solution of 1% sodium
nitrate in water, the nitrate is almost completely decomposed
within 3 hours at a voltage of 2.1 volts and a current efficiency
of 20%.
The composite according to invention, equipped with a catalyst, is
thus excellently suited for the reduction of nitrate compounds,
especially for nitrate degradation in aqueous systems.
EXAMPLE 1.8
If the composite produced according to example 1.6 is impregnated
with a sodium-palladium-tetrachloride/copper-dichloride solution,
the palladium/copper catalyst precipitates according to the
deposition-precipitation process in a fine dispersion on the
surface of the composite. The liquid-phase reduction was carried
out in one variant with sodium formiate at 80.degree. C. and in a
second execution variant with sodium hydroboron at room
temperature. If the composite produced in such a way and equipped
with a catalyst, again connected as a cathode, is dipped with a
graphite anode into a solution of 1% sodium nitrate in water, the
nitrate is almost completely decomposed within 3 hours at a voltage
of 2.1 volts and a current efficiency of 20%.
The composite according to invention, equipped with a catalyst, is
thus excellently suited for the reduction of nitrate compounds,
especially for the nitrate degradation in aqueous systems.
EXAMPLE 1.9
A suspension consisting of 25 g zirconium isopropylate was
hydrolyzed with 20 g water. Subsequently, the resulting
precipitation was peptized with approx. 40 g azotic acid (25%), and
after this was completely dissolved, 25 g aluminum oxide and 25 g
vanadium pentoxide were added and the suspension was stirred until
all agglomerates were completely dissolved. This suspension was
applied on a formed ceramic body such as, for example, a ceramic
tubular membrane with an average pore width of 0.4 .mu.m to a
thickness of 20 .mu.m.
After drying and stabilization of the composite, this composite can
be used for catalytic oxidation reactions such as, for example,
oxidation of SO.sub.2 traces to SO.sub.3 in waste gases, which
subsequently can be eliminated from the waste gas in scrubbers.
EXAMPLE 1.10
A suspension consisting of 25 g tetraethoxysilane in 40 ml ethanol
was hydrolyzed and peptized with 5 g hydrochloric acid (30%). After
a complete hydrolysis, 60 g of an amorphous microporous mixed oxide
system, such as, for example, titanium
dioxide-siliciumdioxide-methylsiliciumsesquioxide glass, was added.
The suspension was stirred until all agglomerates were dissolved,
and the suspension was then sprayed onto a porous inorganic
membrane from Altech to a thickness of 60 .mu.m. After drying and
stabilization of the composite at 250.degree. C. within 20 minutes,
it can be used for catalytic reactions such as the hydroxylation of
benzene to phenol with hydrogen peroxide at 60.degree. C.
Conversion was 1.15%.
EXAMPLE 1.11
A suspension consisting of 15 g tetraethoxysilane and 10 g aluminum
ethanolate in 40 ml ethanol was hydrolized and peptized with 11 g
hydrochloric acid (30%). After a complete hydrolysis, 60 g of a
zeolite in H-form (CBV600 from Zeolyst) was added. The suspension
was only stirred intensively for a short time to avoid destruction
of the zeolite, and it was sprayed onto a porous inorganic membrane
from Atech to a thickness of 60 .mu.m. After drying and
stabilization of the composite at 350.degree. C. within 10 minutes,
this composite can be used for acid catalyzed reactions, such as,
for example, the etherification of alcohols.
* * * * *